While nine northeastern states already subscribe to a cap and trade program for power plants, California's new law caps carbon emissions across industries. The state requires refineries, Big Agriculture, cement, and power plants that emit over 25,000 metric tons of carbon dioxide per year to pay for the right to pollute our air.

U.S. greenhouse gas emissions are already down 7.7% from 2006 even after Congress abandoned cap and trade in 2010. But at least California's law legislatively acknowledges climate change, a potential step toward resurrecting the national discussion to reduce carbon emissions.